The former Norwich City striker had earlier missed a penalty before he headed home in the second half of extra-time to secure a 3-1 victory on the night and a first Conference final berth since 2008.
Kamara revealed his delight at being the match winner in the "do-or-die" game, and praised the Columbus fans for creating such an electric atmosphere at Mapfre Stadium.
"My goal was not as big as the goal that [Ethan Finlay] scored because obviously that goal put us back into it," he told the club's website. "It went in and I was running to the side to celebrate with the fans.
"But [I just felt] sort of relief – you cannot have it any other way. That is just how the game is supposed to go right there. The fans, it was a packed house and they enjoyed every minute of that.
"The energy out there today was amazing. We were feeding off the fans and we were pushing ourselves. We did not want to go to penalties, but for us to be at home, we really fed off the crowd tonight. It sounds like an echo in here but we really did and they were amazing, and we knew we were going to go to overtime."
Crew will face New York Red Bulls in the Eastern Conference final, with the first leg taking place on November 22.